Fats and oils are triacylglycerides, or triglycerides formed by an esterification reaction of fatty acids with glycerol, a trihydroxy alcohol. The distinction between a fat and an oil is arbitrary. At room temperature a fat is solid and an oil is liquid. Most triacylglycerides found in animals are fats, while those in plants tend to be oils.
Fats and oils, the most commonly occurring lipids, are a major source of dietary energy. They contribute about twice as much energy per weight as carbohydrates or proteins.
Metabolically, ingested fats and oils are hydrolyzed into monoacylglycerides, diacylglycerides, fatty acids, and glycerol, all of which can be absorbed through the intestinal wall. The body then (1) utilizes these hydrolyzed or partially hydrolyzed fats as raw materials to synthesize its own fats, (2) converts the fatty acids to other compounds such as carbohydrates or cholesterol esters; or (3) converts the fatty acids to energy. The effects of dietary fats on cholesterol metabolism is of particular interest due to reports which link high levels of cholesterol in the blood (hypercholesterolemia) with arterial disease.
Low fat diets have long been known to be an effective means for lowering the serum-cholesterol level in humans, and, thereby lowering the risk of hypercholesterolemia (see Keys et al., Science. 112, 79 (1950); Melinkoff et al., Am. J. Med Sci., 220, 203 (1950); Groen et al., Voeding, 13, 556 (1952); Keys, Circulation, 5,115 (1952); Keys et al., Clin. Chem., 1,34 (1955).
In 1957, Keys, Anderson and Grande, The Lancet, 2, 959-66, (1957) demonstrated that human serum-cholesterol levels were influenced by the quality of the fats rather than the quantity. It was demonstrated that the intake of saturated fatty acids containing 12 or more carbon atoms produced increased serum cholesterol levels in humans. Unsaturated fatty acids were found to lower serum cholesterol levels.
Grande, Anderson and Keys, Am. J. Clin. Nut., 23 (9), 1184-1193 (1970), disclosed that serum cholesterol and serum phospholipids levels are higher in men having diets rich in palmitic acid (C.sub.16:0) when compared to men having diets rich in stearic acid (C.sub.18:0).
Oils rich in oleic acid are known. For example olive oil is predominently triolein. U.S. Pat. No. 4,460,614--Stratmann, et al. (1984) describes a process for interesterifying tallow and olein. The product is high in unsaturated and polyunsaturated triglycerides.
U.S. Pat. No. 3,900,503--McNaught (1975) discloses fats made by randomly interesterifying sunflower and tobacco seed oils. The products are described as being polyunsaturated oils. Tobacco seed oil and some sunflower seed oil are high in oleic acids. Most sunflower oils are high in linoleic acid.
Swern et al., "Fractionation of Tallow Fatty Acids". The preparation of purified oleic acid and an inedible olive oil substitute, Oil and Soap, (November, 1945) describes the fractionation of tallow into a saturated fraction and an oleic acid fraction. The oleic acid fraction contains 85.7% oleic acid, 4.4% polyunsaturated acids, and 9.9% saturated acids. This fraction can be further purified to yield a 98% oleic acid, 2% saturated fatty acid fraction. The oleic acid is then used to esterify glycerine to make an olein (trioleyl triglyceride).
Vegetable oils are low in cholesterol and high in unsaturated fatty acids both of which are desirable. Yet vegetable oils do not give fried foods a meaty, beefy or tallow flavor which is associated with animal fats, e.g. tallow. The exact identification of what produces this meaty, beefy or tallow flavor has not yet been accomplished. It has recently been discovered that the oleic acid fraction or the unsaturated fatty acid cut of tallow, lard or other animal fats rich in oleic acid can be esterified with glycerine to produce a triglyceride mixture which imparts a tallow or cooked meat flavor to the fried foods and has little or no cholesterol. It is believed that the presence of the C.sub.12 to C.sub.24 mono-unsaturated fatty acids, methyl-branched chain isomers of fatty acids having from 12 to 24 carbons, hydroxy fatty acids, odd chain acids, and polyunsaturated fatty acids contribute to the production of the fried beef or animal flavor during use. These are not necessarily all of the materials which contribute to this flavor.
Therefore, it is an object of this invention to produce a triglyceride which is at least 85% unsaturated, and which contains some mixed esters of fatty acids, including mono and poly-unsaturated, methyl-branched chain, odd chain, hydroxy fatty acids and other unidentified minor fatty acids typically present in tallow.
This composition imparts a beefy or tallow flavor to foods fried in this synthetic triglyceride without adding cholesterol to the foods.
These and other objects of the invention will be evident from the description herein.
All percentages are by weight unless otherwise indicated.